1. Field of the Invention
The present invention relates to an apparatus for surveillance of bus-bar temperature which surveys occurrence of a temperature rise at a connection part of the bus-bars in high-tension or low-tension parts of a switch board or a control board.
2. Description of the Prior Art
A conventional surveillance of temperature of bus-bar is described referring to FIG. 3. FIG. 3 is a perspective view showing the conventional surveillance of temperature of bus-bar. In FIG. 3, bus-bars 1 and 2 are electrically and mechanically connected via a connection bar 3 by screwbolts 4, washers 5 and nuts (which are not shown in the figure because they are well-known). The bus-bar 2 is fixed on an insulative holder 8 by a screwbolt 6, a washer 7 and a nut (not shown in the figure). Furthermore, the insulative holder 8 is fixed on a frame 11 by screwbolts 9, washers 10 and nuts (not shown in the figure). On each connection bar 3, a thermolabel 12 is adhered for detecting a temperature rise of the connection part of the bus-bar 1 and 2.
Generally, contact resistance of the connection part of the bus-bars 1 and 2 and connection plate 3 or the like may be increased due to corrosion of the surfaces of the bus-bar 1 and the connection plate 3 and/or the surfaces the bus-bar 2 and the connection plate 3 or loosening of the screwbolts 4. And thereby, the temperature of the connection parts (connection plate 3) of the bus-bars 1 and 2 may rise. When the temperature at the connection plate 3 rises, the color of the thermolabel 12 changes. When the change of the color of the thermolabel 12 is observed, the abnormal temperature rise at the connection part of the bus-bars 1 and 2 is detected.
In the above-mentioned conventional surveillance of the temperature of the bus-bars, since the abnormal temperature rise at the connection part of the bus-bars 1 and 2 is detected by the change of the color of the thermolabel 12, the occurrence of the abnormal temperature rise is confirmed ex post facto. Accordingly, occurrence of the abnormal temperature rise at the connection part of the bus-bars 1 and 2 can not be predicted in advance.
Furthermore, the connection part of the bus-bars 1 and 2 are covered by a housing, such as a security cover and so on. Thereby, for confirming the occurrence of the abnormal temperature rise, the cover or front panel of the housing must be taken off in a troublesome manner each time.